Multi-source distributed navigation system architecture

ABSTRACT

A distributed navigation system includes navigation platforms, each having a universal navigation processor, relative navigation systems to provide source information to the navigation platforms, navigation filters provided on one or more of the universal navigation processors, and an anchor navigation node disposed on one or more of the navigation platforms to form one or more anchor navigation platforms. Each anchor navigation node includes an inertial navigation system, a clock, and absolute navigation systems, which are used, in combination with source information, to determine navigation information. The anchor navigation platforms provide the navigation information to other navigation platforms. The system further includes a navigation processor system in communication with the universal navigation processors to provide operating information updates to the universal navigation processors and a graphical user interface to display the navigation information to a user and permit the user to review and control the navigation information.

RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.16/177,419, entitled “Multi-Source Distributed Navigation SystemArchitecture” and filed Oct. 31, 2018, which is a continuation-in-partapplication of U.S. application Ser. No. 15/494,898, entitled“Multi-Source Distributed Navigation System Architecture” and filed Apr.24, 2017, which are hereby incorporated by reference in theirentireties.

TECHNICAL FIELD

The present invention relates to navigation system architectures, andmore particularly, to distributed navigation system architectures withmultiple platforms.

BACKGROUND

Objects or navigation platforms, such as airplanes, motor vehicles, andnaval vessels, use navigation systems to navigate to desireddestinations. These navigation systems are typically dependent onGPS-aided inertial navigation systems (INS), which include performanceerrors, such as drift. Although some navigation systems add other aidingmechanisms, such as RF aids, celestial sightings, or magnetic compass,the combination of aiding mechanisms do not provide better updates thanthe GPS/INS system alone.

SUMMARY OF THE EMBODIMENTS

In accordance with one embodiment of the invention, a distributednavigation system includes a plurality of navigation platforms, eachnavigation platform having a universal navigation processor configuredto communicate with other universal navigation processors overdistribution channels in a communication network. The distributednavigation system also includes one or more relative navigation systems,in communication with the universal navigation processors, configured toprovide source information to the navigation platforms. The distributednavigation system further includes one or more navigation filtersprovided on one or more of the universal navigation processors, eachnavigation filter configured to process the source information, ananchor navigation node disposed on one or more of the plurality ofnavigation platforms in order to form one or more anchor navigationplatforms. The anchor navigation node includes an inertial navigationsystem, a clock, and one or more absolute navigation systems and isconfigured to determine navigation information based on the inertialnavigation system, the clock, the one or more absolute navigationsystems and the source information. The one or more anchor navigationplatforms provide the navigation information over the distributionchannels to the other navigation platforms in the communication network.The distributed navigation system further includes a navigationprocessor system in communication with each of the universal navigationprocessors in the communications network in order to provide operatinginformation updates to the universal navigation processors and agraphical user interface configured to display the navigationinformation to a user and permit the user to review and control thenavigation information.

In related embodiments, the graphical user interface may be disposed onat least one of the one or more anchor navigation platforms. At leastone of the one or more navigation filters may include (a) a situationmodule configured to provide situation data, (b) an information moduleconfigured to determine an estimate of the quality and an estimate ofthe integrity of the source information, at a given time, based on thesource information received from one or more data sources and based onthe situation data received from the situation module, (c) an integritymonitor module configured to receive the estimate of the quality and theestimate of the integrity of the source information from the informationmodule and to receive the source information from the one or more datasources, configured to determine the integrity and the quality of thesource information based on the estimate of the quality and the estimateof the integrity of the source information from the information module,and configured to validate the source information based on (1) theintegrity of the source information, and/or (2) the quality of thesource information, and (d) a navigation state estimator configured todetermine the navigation information of the one or more navigationplatforms based on the source information that was validated andcorresponding quality of the source information received from theintegrity monitor module. The situation module may be configured toreceive, from the graphical user interface, an instruction from the userand to provide the instruction to the information module as situationdata. The instruction may modify a mission plan to maximize performanceof one or more of the plurality of navigation platforms or modify amission plan to maintain an estimated arrival time at a destination ofone or more of the plurality of navigation platforms. The situation datamay be based on past or current performance of the one or more datasources or one or more of the plurality of navigation platforms or maybe based on past or current performance of the one or more data sourcesor one or more of the plurality of navigation platforms in ageographical region that overlaps with a mission plan. The situationmodule may receive the situation data from databases with storedsituation data previously known, from communication links with updatedsituation data that changes over time, from the one or more datasources, from detection systems that provide the situation data based ondetected conditions, and/or from a user that inputs modifications to thesituation data. The situation data may include environment conditions,position information, velocity, attitude, temporal information, platformconfiguration, mission phase, data source location, system health,mission plan, threat data, condition of a threat, threat operatingcapabilities, threat location, temperature, cloud cover, visibility,barometric pressure, terrain, time of year, tides, radiationenvironment, population, city information, street information, buildinginformation, known transmitters, known vehicles, visible stars, and/orlocation of satellites in the sky. The graphical user interface may beconfigured to display a modification generated autonomously by an anchornavigation platform. The modification may include changes to a missionplan to maximize performance of one or more of the plurality ofnavigation platforms or may include changes to a mission plan tomaintain an estimated arrival time at a destination of one or more ofthe plurality of navigation platforms. The graphical user interface maybe configured to display information related to past or currentperformance of one or more of the plurality of navigation platformsconducting a mission. The graphical user interface may be configured todisplay contributions from the one or more data sources to thenavigation information for one or more of the plurality of navigationplatforms conducting the mission. The navigation information may includeposition, velocity, altitude, errors in position, errors in velocity,errors in attitude, time, clock errors, propagation delays, GPSsatellite errors, sensor errors, sensor characterization parameters orany combination thereof. The one or more absolute navigation systems mayinclude a global positioning system (GPS), a celestial object sightingsystem (COSS), a magnetic compass, and/or an RF sensor system. The oneor more relative navigation systems may include a vision system havingan image sensor. The plurality of navigation platforms may includemoving and non-moving platforms.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of embodiments will be more readily understood byreference to the following detailed description, taken with reference tothe accompanying drawings, in which:

FIG. 1 schematically shows a distributed navigation system architectureaccording to embodiments of the present invention;

FIG. 2 schematically shows another distributed navigation systemarchitecture according to embodiments of the present invention;

FIG. 3 schematically shows various navigation platforms in a distributednavigation system architecture according to embodiments of the presentinvention;

FIG. 4 schematically shows a navigation platform with an anchornavigator in a distributed navigation system architecture according toembodiments of the present invention;

FIG. 5 schematically shows a navigation platform in a distributednavigation system architecture according to embodiments of the presentinvention;

FIG. 6 schematically shows a navigation filter used within a universalnavigation processor according to embodiments of the present invention;and

FIGS. 7, 8 and 9 schematically show a distributed navigation systemarchitecture using a navigation filter and environments in which thearchitecture may operate according to embodiments of the presentinvention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Definitions. As used in this description and the accompanying claims,the following terms shall have the meanings indicated, unless thecontext otherwise requires:

“Navigation platform” refers to an object that may move, such as anaircraft, a vehicle, a naval vessel, etc. and a stationary object, suchas a building or base, etc., that uses navigation information.

“Navigation information” may include the geolocation position, velocity,altitude, errors in position, errors in velocity, errors in attitude,time, clock errors, propagation delays, GPS satellite errors, sensorerrors, and/or sensor characterization parameters, by way of example.

“Data source” refers to a source of data that provides information thatmay be used to determine the navigation information of one or moreobjects.

“Source information” refers to information provided by a data source.

“Integrity of source information” refers to a measure of sourceinformation related to whether the source information is trustworthy andfrom a data source that is performing as intended, e.g., the data sourceis not subjected to interference or jamming, and thus the sourceinformation is not altered in some way.

“Quality of source information” refers to a measure of sourceinformation related to whether a data source is providing the sourceinformation according to its specifications without any degradation, ora measure of source information that specifies the accuracy of thesource information at a given time.

An “absolute navigation system” includes navigation systems such as aGlobal Positioning System (GPS) and/or Celestial Object Sighting System(COSS) that provide absolute position and current time navigationinformation from data sources such as satellites and celestial objects.

A “relative navigation system” includes navigation systems such asvision systems that provide relative position and current timenavigation information from data sources such as man-made landmarks,e.g., buildings, streets, etc., and/or terrestrial landmarks, e.g.,mountains, bodies of water, etc.

Distributed Navigation System Architecture

FIG. 1 schematically shows a distributed navigation system architecture10, according to embodiments of the present invention, that includes aplurality of navigation platforms 12. The distributed navigation systemarchitecture 10 may include moving navigation platforms 12, non-movingnavigation platforms 12, or a combination thereof. The moving navigationplatforms 12 may be assigned to one or more missions. Each navigationplatform 12 has a universal navigation processor 14 configured tocommunicate with other universal navigation processors 14 overdistribution channels 15 in a communication network.

The distributed navigation system architecture 10 further includes ananchor navigator 16 or anchor navigation node disposed on one or more ofthe plurality of navigation platforms 12 in order to form one or moreanchor navigation platforms. The anchor navigator 16 includes aninertial navigation system 20, a clock 28, and one or more absolutenavigation systems 22, 24, 26 and is configured to determine navigationinformation based on the inertial navigation system, the clock, the oneor more absolute navigation systems and optionally source informationfrom one or more relative navigation systems. As shown in FIG. 1 , theuniversal navigation processor 14 of the anchor navigator 16 isconfigured to have a graphical user interface with a display 17. Thegraphical user interface may display, for example, navigationinformation for the user of the anchor navigator 16 to review andoptionally control. The graphical user interface may be configured toaccept user inputs, such as additional situational data as described inmore detail below. For example, the user inputs may make modificationsto a mission plan, which in turn modifies the navigation information.FIG. 1 shows a distributed navigation system architecture 10 with onenavigation platform 12 having an anchor navigator 16 and FIG. 2 shows adistributed navigation system architecture 10 with two navigationplatforms 12 having an anchor navigator 16. Although FIGS. 1 and 2 showthree navigation platforms 12 with one or two anchor navigationplatforms, any number of the navigation platforms 12 may be used, andany number of navigation platforms 12 may include an anchor navigator16.

The one or more navigation platforms 12 with the anchor navigator 16,i.e., the anchor navigation platforms, know its own position and currenttime to within GPS precision at all times regardless of which navigationaiding sensors or data sources 105 are available or regardless of whichdistribution channels 15 are open. The one or more anchor navigationplatforms provide its navigation information to the other navigationplatforms 12 in the communication network that do not include an anchornavigator 16 or anchor navigation node. For example, FIG. 3schematically shows exemplary navigation platforms 12 that include ananchor navigator 16 and do not include an anchor navigator 16 in adistributed navigation system architecture 10.

The distributed navigation system architecture 10 further includes anavigation processor system 18 in communication with each of theuniversal navigation processors 14 in the communications network inorder to provide operating information updates to the universalnavigation processors 14. For example, software updates may be sent fromthe navigation processor system 18 to the universal navigationprocessors 14 on a periodic basis. The software updates that are sent tothe universal navigation processors 14 may include process informationfor determining and/or estimating navigation information as discussed inmore detail below. In various embodiments, the program code for theuniversal navigation processors 14 may also relate to how the navigationplatforms 12 distribute information among the navigation platforms 12 inthe network. Furthermore, the program code may relate to protocols forcommunication among the navigation platforms 12.

The distributed navigation system architecture 10 may be used as abaseline architecture for all future distributed navigation systemdesigns, irrespective of how many aiding modalities are incorporatedinto the architecture or how many navigation platforms 12 anddistribution channels 15 are used in the communication network. Theindividual navigation platforms 12 may include their own dedicatedsensors or data sources 105 and may be added to or removed from thedistributed navigation system architecture 10 with minimal effort sincesoftware code does not need to be revised when scaling up to a largedistributed navigation system architecture. Embodiments of the presentinvention provide a unique distributed navigation system architecturethat includes absolute (e.g., global positioning system (GPS)-classpositioning and time) navigation information to all navigation platforms12 within the network when GPS is present, and also includesGPS-alternative navigation information to all navigation platforms 12when GPS is not present or the navigation platforms 12 are not updatedwith the navigation information from the anchor navigation platform(s)by combining absolute navigation systems (e.g., GPS and/or celestialobject sighting system (COSS) with other aiding modalities, such asmagnetic compass and/or an RF sensor system) with relative navigationsystems (e.g., vision systems). The distributed navigation systemarchitecture 10 uses the common universal navigation processor 14 on allof the navigation platforms 12, which permits large numbers ofnavigation aiding modalities and network nodes to be used in anefficient state fusion based approach that achieves nearly optimalperformance with minimal computational effort.

The Navigation Platforms

FIG. 4 schematically shows a navigation platform 12 with an anchornavigator 16 and FIG. 5 schematically shows a navigation platform 12that does not include an anchor navigator 16 in a distributed navigationsystem architecture. As mentioned above, the anchor navigator 16includes an inertial navigation system 20, a clock 28, and one or moreabsolute navigation systems 22, 24, 26. For example, the inertialnavigation system 20 may include accelerometers and/or gyroscopes. Theclock 28 may enable the anchor navigator 16 to update or synchronize thetime associated with the navigation information with an external clock.Exemplary clocks include atomic clocks, microwave transition clocks,optical transition clocks, and/or astronomic-based clocks (e.g.,pulsar). The one or more absolute navigation systems 22, 24, 26 mayinclude a global positioning system (GPS) 22 that requests and receivesnavigation information from one or more satellites or data sources 105in a satellite system, a celestial object sighting system (COSS) 24 thatreceives navigation information from one or more celestial objects ordata sources 105, or other navigation modalities 26, such as an RFsensor system and/or magnetic compass that communicate with data sources105 to provide navigation information for the navigation platforms 12.

Any of the navigation platforms 12 may become anchor navigationplatforms depending on the network and distributed navigation systemarchitecture application. For example, a first navigation platform 12may initially be an anchor navigation platform in the network and then asecond navigation platform 12 may become an anchor navigation platforminstead of, or in addition to, the first navigation platform 12.

Each of the universal navigation processors 14 in the anchor navigationplatform or the other navigation platforms 12 includes a navigationfilter 30 configured to process source information from one or more datasources 105 or from data sources 105 associated with the absolutenavigation systems 22, 24, 26 to estimate the navigation information forone or more navigation platforms 12. The universal navigation processor14 may store previously estimated navigation information for thenavigation platforms 12 in memory or storage, estimate a relative changein navigation information based on at least source information from thedata sources 105, and update the estimated navigation informationaccordingly.

The navigation filters 30 may include an extended Kalman filter, aparticle filter, a nonlinear moment filter, a Hidden Markov Model,and/or a Bayesian filter. The universal navigation processor 14 mayimplement vision-based odometry from a relative navigation system thatincludes a vision sensor. For example, the vision sensor may be used tocapture a succession of images e.g., images of a man-made landmarkand/or terrestrial landmark, and then the image information used tointerpolate a change in the geolocation position of the navigationplatform 12. For example, the universal navigation processor 14 mayidentify one or more features that are present in a series of images totrack. For instance, if the navigation platform 12 is an aircraft flyingover a segment of a river, the universal navigation processor 14 mayselect a particular bend in the river as the feature to track. Theuniversal navigation processor 14 may determine the changing position ofthe bend in the river in successive images until the feature disappears,and apply the navigation filter 30 to this data to estimate a change inthe geolocation position of the one or more navigation platforms 12. Inanother example, the aircraft may be flying by a mountain range and theuniversal navigation processor 14 may select a particular mountain peakas the feature to track. The universal navigation processor 14 may applythe navigation filter 30 to the changing position of the selected peak.

In another example, the universal navigation processor 14 may receivesource information from the inertial navigation system 20, e.g.,accelerations and angular rates from accelerometers and gyroscopes, andintegrate this source information over a period of time to estimate arelative change in the geolocation position of the one or morenavigation platforms 12. However, accelerations and angular ratesinherently exhibit drift errors (e.g., misalignment and bias errors)which can compound over time. As a result, the accuracy of the estimatedrelative change in the geolocation position may deteriorate over time.To compensate for the drift errors, the one or more navigation platforms12 receive navigation information from the other navigation platforms12, such as the anchor navigation platform and/or other navigationplatforms 12.

In some embodiments, data sources 105 that provide source informationmay be located on and/or distributed across multiple navigationplatforms 12. Alternatively, or in addition, data sources 105 may befound in different parts of the environment, such as underground,underwater, terrestrially, in the atmosphere, and/or in space.

Overview of the Navigation Filter System

FIG. 6 schematically shows a navigation filter system 100 that may beused as the navigation filter 30 within the universal navigationprocessor 14 for determining navigation information for one or morenavigation platforms 12 using source information validated on the basisof its quality and/or integrity, and FIGS. 7-9 schematically show adistributed navigation system architecture 10 using a navigation filtersystem 100 and environments in which the architecture may operate. Thenavigation filter system 14 is described in U.S. patent application Ser.No. 15/435,412 filed on Feb. 17, 2017, which is incorporated byreference herein in its entirety.

Embodiments of the navigation filter system 100 provide the bestpossible navigation information resulting from several data sources 105or sensors, for example, in an environment in which one or more of thosesources may be challenged, contested, degraded, or denied and,preferably, to do so without human intervention. Data sources in such anenvironment may provide widely varying navigation information qualityand integrity depending on the challenges presented by the environment.In addition, the source information provided by some of the data sourcesmay be challenged or compromised, such that the data sources have goodperceived quality but, in fact, lack integrity, e.g., the sourceinformation has been compromised or altered in some way. Embodiments ofthe present navigation filter system 100 are capable of identifying boththe quality and integrity of data sources based on the environment andusing this quality and integrity information in the navigationinformation accordingly. In addition, identification of quality andintegrity of data sources is not static but instead may change over timedepending on many factors, e.g., mission phase, location, and systemhealth. Embodiments of the present navigation filter system 100 maintainawareness of the situation in which the data sources 105 are operatingand maintain information model(s) describing the dynamic andprobabilistic state of the source information when the situation inwhich the source information is obtained is fully known and aprobabilistic state representing the uncertainty associated with thesource information when the situation is uncertain.

For example, in both government organizations and commercialenterprises, navigation information is critical for successfullycompleting particular objectives. For instance, pilots and/or dronesconducting missions on behalf of the military or intelligence agenciesmust know their geolocation positions to obtain meaningful information.Extraction teams tasked with rescuing civilian and military hostagesmust track their geolocation positions and times to ensure that theyreach their targeted destination at the designated times. Autonomousrobots deployed to search, unearth, and/or defuse land mines inpreviously war-torn regions risk triggering explosions if they fail toevade known land mines. Commercial pilots conducting transoceanicflights must rely on their instruments for geolocation position becausetheir environments may generally lack identifying geographical features(e.g., mountain ranges, distinct coast lines). Energy companies may sendautonomous vehicles into remote and/or dangerous environments to repairor maintain equipment.

Although the Global Positioning System (GPS) is the most commonly usedabsolute navigation system for providing a navigation platform with itsnavigation information, the GPS system is not always available or may beunreliable. For example, in some situations, the navigation platform 12may be proximate to an insufficient number of GPS satellites. In othersituations, a particular environment may interfere with the navigationplatform's ability to communicate with the satellites, despite theirnumber and location (e.g., mountains that deflect or degrade signals).Further, a navigation platform 12 may be subject to other types ofinterference, such as hostile organizations intent on spoofing orjamming GPS signals to prevent the navigation platform from obtainingaccurate navigation information.

Redundant navigational capabilities decrease a navigation platform'svulnerability to erroneously determined navigation information. Otherdata sources 105, such as data sources from relative navigation systems,may supplement and/or replace GPS signals in determining the navigationinformation. However, depending on the navigation platform's situation,information from one or more of these data sources may be unreliable.Like GPS, these data sources may function improperly and thereby outputsource information of dubious integrity, and they are also vulnerable toexternal interference. Thus, additional data sources may not, in and ofthemselves, guarantee more accurate navigation information. Furthermore,because the reliability of any given data source 105 changes dynamicallybased on the data source's situation, ensuring that reliable sourceinformation is solely used to determine navigation information becomes amore challenging endeavor.

Embodiments of the present invention evaluate source information fromone or more data sources 105 and situation data to determine which datasources 105 can be relied on for determining the navigation informationof one or more navigation platforms 12. Referring to FIG. 6 , thenavigation filter system 100 includes multiple data sources 105 (shownas 105 a, 105 b, . . . , 105 k) that provide source information that maybe used to determine a navigation platform's navigation information.Because one or more of the data sources 105 may not be reliable at anygiven time, the navigation filter system 100 may use a situation module130, an information module 130, an integrity monitor module 110, and anavigation state estimator 115, as described in more detail below, toidentify the data sources 105 that should be relied on.

In particular, the situation module 130 provides situation data 125related to the data sources' situation, and the situation module 130 mayaggregate the situation data 125 and send it to the information module120. The information module 120 creates and/or maintains statisticalmodels for estimating the quality and/or integrity of source informationfrom any given data source 105, and uses these models with the situationdata (and in some scenarios, source information as well) to determinethe estimates of quality and integrity. The information module 120provides the estimates to the integrity monitor module 110.

The integrity monitor module 110 makes the final determination of thedata sources 105 that, at that particular time, should be relied on todetermine the navigation information for the plurality of the navigationplatforms (also referred to herein as “validating” the information froma particular data source). The integrity monitor module 110 may validateany source information based on its integrity and/or quality, and mayfurther determine integrity and/or quality based on information from thedata sources 105 (e.g., the source information, quality of the sourceinformation, integrity of the source information), information from aninformation module 120 (e.g., an estimate of the quality and/or anestimate of the integrity of the source information, at a given time),or both.

The integrity monitor module 110 sends the validated source informationto the navigation state estimator 115, and in some embodiments, theintegrity monitor module 110 refrains from sending source informationthat has not been, and will not be, validated. The navigation stateestimator 115 uses the validated source information to determine thenavigation information, which may be transmitted to the one or morenavigation platforms 12. In some embodiments, the navigation stateestimator 115 may also transmit the navigation information to a display17 for a user to view and optionally control the navigation informationor to other systems, e.g., within one or more of the navigationplatforms 12 (not shown). Furthermore, the navigation state estimator115 may transmit the navigation information back to the integritymonitor module 110, where it may be used to validate subsequent sourceinformation received from the data sources 105 and/or information module120.

As shown in FIGS. 7-9 , the various components of the navigation filtersystem 100 may be located on one or more navigation platforms 12 in oneor more locations. For example, the situation module 130, informationmodule 120, integrity monitor module 110, and/or navigation stateestimator 115 may be coupled to a navigation platform 12 having theanchor navigator 16 (as shown in FIG. 8 ) and/or may be remotely locatedfrom the anchor navigation platform on another navigation platform 12,e.g., on a moving or non-moving navigation platform 12. Alternatively,the components of the navigation filter system 100 may be distributedacross multiple navigation platforms 12 (as shown in FIG. 9 ), e.g., onmoving platforms and/or non-moving platforms 12.

As mentioned above and shown in FIGS. 1 and 2 , the universal navigationprocessors 14 of the anchor navigators 16 may include graphical userinterfaces with displays 17 for a user to review the navigationinformation and optionally control the navigation information. Althoughthe anchor navigation platforms are shown with the displays 17, any ofthe navigation platforms 12 in the distributed navigation systemarchitecture 10 may include a graphical user interface with a display17, although the ability to control the navigation information throughthe display 17 may be limited to just selected navigation platforms,e.g., one or more anchor navigation platforms.

For example, the graphical user interface may accept user inputs tomodify situation data, e.g., to modify a mission plan. The graphicaluser interface may display one or more objectives for the modifications.In response to user selection of at least one objective, the universalnavigation processor 14 may send the modifications as situation data 125to a situation module 130, and a navigation filter 30 may use thisinformation (as explained above) to provide updated navigationinformation to the one or more navigation platforms 12 that may beconducting the mission.

One objective may be to maximize the performance of the one or morenavigation platforms 12. For example, during a prior, completed mission,the data sources 105 and/or one or more navigation platforms 12 may haveperformed poorly in one or more particular geographical regions, andthus caused one or more navigation platforms 12 conducting the missionto be inefficient, e.g., take longer than expected or not reach theright destination. Upon receiving updated navigation information from ananchor navigator 16, the navigation platform 12 adjusts its navigationinformation, e.g., direction and/or velocity, to improve the performanceof the one or more navigation platforms 12.

Another objective for modifying situation data 125, such as a missionplan, may be to maintain the expected completion time of the mission(e.g., expected arrival time at the destination). Because the conditionsunder which a navigation platform 12 operates during a mission mayresult in errors or inefficiencies, costing the navigation platform 12additional time to get to its destination, the universal navigationprocessor 14 may provide historical performance of the data sources 105and/or one or more navigation platforms 12 at different locations alongthe route. The historical performance data may be supplied as situationdata 125 to the situation module 130 and a navigation filter 30 may usethis information to provide updated navigation information to the one ormore navigation platforms 12 to maintain the expected completion time ofthe mission.

Alternatively, instead of selecting one or more objectives from adisplay 17 of a graphical user interface, the user may directly inputmodifications to situation data 125, e.g., modifications to the missionplan, which ultimately modifies the navigation information provided tothe one or more navigation platforms 12. For example, the user maychange one or more portions of the mission plan to avoid particulargeographical regions, such as regions projected to experience dangerousweather conditions during the mission. In another example, the user maydelay the estimated departure time for the mission, or alter thevelocity and/or altitude at which a navigation platform 12 may travel.As mentioned above, the modifications may be sent as situation data 125to a situation module 130, and a navigation filter 30 may use thisinformation to provide updated navigation information to the one or morenavigation platforms 12.

In further embodiments, the universal navigation processor 14 of theanchor navigator 16 may be configured to modify situation data 125,e.g., the mission plan, based on any of the objectives presented to theuser in the graphical user interface. The universal navigation processor14 may also be configured to automatically modify mission plans. Theuniversal navigation processor 14 may modify the mission plan, e.g.,within a predetermined period of time before the expected departure timeof the mission, to ensure that the modifications are based on the mostupdated navigation information from the navigation filter 30. Forexample, the universal navigation processor 14 may be configured tomodify all mission plans originating from the same location as itsanchor navigator 16 when the situation data shows that particulargeographical regions have become, or are expected to become, unsafe fortravel. In this case, the navigation information may reroute one or morenavigation platforms 12 and/or abort the mission altogether to avoidunacceptable risks to personnel.

The universal navigation processor 14 of the anchor navigator 16 maysend the modifications to the situation data 125 to a situation module130, and a navigation filter may use this information to provide updatednavigation information to the one or more navigation platforms 12. Themodifications may be sent to one or more navigation platforms 12 thatare conducting the mission and/or to one or more navigation platforms 12that will communicate with the navigation platforms 12 that areconducting the mission, such as stationary navigation platforms 12 ornavigation platforms 12 positioned along the route of the mission.

The one or more navigation platforms 12 may periodically receive updatednavigation information, which implements changes to the mission plan,and additional navigation information that may be generated before,during and/or after the mission. One or more anchor navigation platformsand/or one or more navigation platforms 12, e.g., platforms conductingthe mission, may provide situation data 125 concerning the mission tothe graphical user interface before, during and/or after the mission.The display 17 may show a comparison of the absolute navigationinformation to the navigation information determined by one of itsnavigation filters 30, and the user may review and assess theperformance of the data sources 105 and/or the one or more navigationplatforms 12.

For example, the user may review and evaluate, for every data source105, its respective contribution to the determined navigationinformation. For instance, the display 17 may show the contribution froma satellite 105, a celestial object sighting system (COSS) 24, an RFsensor system 105, a magnetic compass 105, or any of the other datasources 105 described herein. The display 17 may show the current and/orpast performance of the data sources 105 and/or the one or morenavigation platforms 12 to the user. The user may evaluate the overallperformance of one or more navigation platforms 12, and the performanceof individual data sources with respect to its integrity and/or quality,and decide to control the navigation information.

The display 17 may show a comparison between the current performance andpast performance of the data sources 105 and/or the one or morenavigation platforms 12 (i.e., performance during previously completedmissions) for the same geographical region. The universal navigationprocessor 14 may store situation data 125 about the performance of thedata sources 105 and/or the one or more navigation platforms 12. Thedisplay 17 may show the accumulated performance data to the user.

Data Sources for the Navigation Filter System

As described above, the navigation filter system 100 for one or morenavigation platforms 12 may include numerous data sources 105. A datasource 105 may be any sensor or source that provides source informationused to determine a navigation platform's navigation information. Forexample, the data sources 105 may be vision sensors, laser-basedsensors, and/or GPS sensors. Other examples include chemical sensors,such as directional chemical sensors or particulate sensors. Additionalexemplary sensors include gravity-based sensors (e.g., utilizing agravimeter), RF-based sensors (e.g., utilizing radio frequency (RF)detectors, cellular detectors, WiFi detectors, Bluetooth® detectors),electromagnetic-based sensors in other parts of the spectrum (e.g.,microwave detectors, X-ray detectors, electrical field strengthdetectors, infrared, radar), barometers, magnetic sensors (e.g.,utilizing a magnetic field sensor, a magnetometer, an induction coil, amagnetic resonator, magnetic compass), torque and acceleration sensors(e.g., gyroscopes, accelerometers), force sensors (e.g., vibrationsensors, pressure sensors, inertial sensors), light sensors (e.g.,optical detectors, CMOS sensors, laser system detectors), acousticsensors (e.g., sonar, ultrasound), celestial navigation sensors (e.g.,star trackers), celestial objects, (e.g., stars, planets) and thermalsensors, among others. An electronic support measures (ESM) systemand/or a celestial object sighting system (COSS) may also be datasources 105.

In some embodiments, data sources 105 may be located on a navigationplatform 12 or distributed across multiple navigation platforms 12.Alternatively, or in addition, data sources 105 may be deployed indifferent parts of the environment, such as underground, underwater,terrestrially, in the atmosphere, and/or in space.

Situation Module

As described above, the situation module 130 provides the situation data125 to the information module 120. The situation module 130 mayaggregate situation data 125 before sending it to the information module120. In some embodiments, the situation module 130 establishescommunication links with external systems that provides situation data125 regarding a navigation platform's and/or data sources' environmentin real-time. In various embodiments, the situation module 130 iscoupled to one or more input devices that respond to user input ofsituation data 125. Examples of such input devices include graphicaluser interfaces that may have a display 17 or manual controls.

For example, the situation module 130 may capture situation data 125provided by external sources (e.g., communication links/distributionchannels 15) regarding the integrity of particular data sources 105(e.g., a particular sensor is known to be not operating as indicated byits quality measure or is compromised with the same result). Thesituation module 130 may also capture other relevant situation data 125provided by other systems, e.g., systems on the same navigation platform12 that include the navigation filter system 100 and/or a differentnavigation platform 12, such as information that may be provided by anElectronic Support Measures (ESM) system. For example, an ESM system mayidentify electromagnetic signals that may interfere with data sources105, and this situation data 125 should thus be considered by theinformation module 120 when determining data source(s) 105 integrityand/or quality.

For example, during a mission, the navigation filter 30 may providenavigation information 36 about one or more navigation platforms 12 tothe display 17 of a graphical user interface. The navigation information36 may include the current status and projected status of the one ormore navigation platforms 12 along the planned route, the situationalawareness picture, including active and potential threat systems oreffects along the planned route, the current and/or projectedperformance of the data sources 105 due to the situation or environmentalong the planned route. For example, the display 17 may show the datasources 105 providing source information to the navigation platform 12and descriptions of the integrity and/or quality of each data source105. The data sources 105 may be displayed in order of their reliability(e.g., data sources 105 providing high integrity, high quality sourceinformation first, and data sources 105 providing low integrity, lowquality source information last).

The display 17 may also provide known and expected situations along theplanned route, as well as the current and expected impact of thesituations on the integrity and/or quality of the source informationfrom the data sources 105. The situations may be organized according toproximity to the navigation platform 12. For example, if the missionplan has one or more navigation platforms 12 traversing a mountain rangeand then entering a region known to be occupied by a hostileorganization, the display 17 may show these situations in that order.Within the display of situations currently applicable to the navigationplatform 12, the situations may be organized by the severity of theirimpact on the data sources 105. For example, if the one or morenavigation platforms 12 are traversing a mountainous region that iscurrently experiencing heavy fog and that is also known to be occupiedby a hostile organization that may spoof GPS signals, then both of thesesituations may be shown on the display 17 as impacting the integrityand/or quality of the source information from the data sources 105. Forinstance, the mountains may cause the GPS signals to be intermittent andthe fog may degrade the navigation platform's 12 vision sensors 105.Thus, the display 17 may show the lack of integrity of GPS signalsobtained in this region due to the hostile organization and may show thelack of integrity of GPS signals and the vision sensor signals obtainedin this region due to the environmental conditions. The user may reviewthe navigation information of the one or more navigation platforms 12 onthe display 17 before, during and/or after a mission and may optionalcontrol the navigation information by providing additional user inputsthrough the graphical user interface. For example, the user may reviewnavigation plan modifications in order to make sure that properperformance is attained. The navigation plan modifications may begenerated by the user, by the one or more navigation platforms 12autonomously, or by some higher authority. The navigation informationmay be reviewed on the display 17 in several modes, e.g. maximumperformance of the one or more navigation platforms 12,time-to-destination, etc. The display 17 may also have analytical toolsthat allow various components in the distributed navigation systemarchitecture 10 to be monitored, e.g., IMU only, celestial data sourcesonly, etc. and may provide a history or log of the performance of theone or more navigation platforms 12, and comparison of the current andhistorical performance of the one or more navigation platforms 12 in thesame mission area.

Various types of situation data may include environment conditions(e.g., reports about inclement weather in a territory that the object ordata source is expected to pass through), position information, temporalinformation, platform configuration, mission phase, data sourcelocation, system health, mission plan, threat data (e.g., an alert froma vehicle or an agency that a newly launched enemy mission has beendetected within the navigation platform's or data sources' vicinity),condition of a threat, threat operating capabilities, threat location,temperature, cloud cover, visibility, barometric pressure, terrain, timeof year, tides, radiation environment, population, city information,street information, building information, known transmitters, knownvehicles, visible stars, and/or location of satellites in the sky, aswell as any situation data that would be beneficial to the navigationfilter system 100, as known by one of ordinary skill in the art.Situation data may also include any of the navigation informationdescribed herein, e.g., velocity and attitude.

In some embodiments, situation data 125 may be stored in one or moredatabases. The database(s) may include previously received situationdata (e.g., apriori) and/or real-time situation data (e.g., dynamic).The databases may include data stored at the beginning of the navigationplatform's travel. The databases may store situation data for one ormore of the navigation platforms 12 and/or data source(s) for apredetermined period of time, e.g., the past three hours. As thedatabases receive additional situation data, the databases may overwritesome of the previously stored data or aggregate the data. In someembodiments, the databases may store different types of situation datafor different lengths of time (e.g., tides for the past two hours,weather-related data for the past hour, etc.).

The Information Module

The information module 120 describes the integrity and the quality ofthe source information from the data source(s) 105 based on a dynamic,statistical representation of the situation data 125 in combination withthe quality and integrity information supplied by the data source(s) 105for the current time. The situation data 125 received from the situationmodule 130 may be based on apriori situation data, updates provided bycommunication links, and the source information provided by each of thedata sources 105. The information module 120 creates or providesstatistical models to determine an estimate of quality and/or anestimate of integrity, which the information module 120 provides to theintegrity monitor module 110. The information module 120 maintains themodels (e.g., profiles, statistics) of all data that may influence thenavigation state estimator 115, e.g., given the navigation state is{circumflex over (X)}_(n), the likelihood data source 105 i iscompromised and should be discarded is a. For example, the informationmodule 120 maintains statistics on data source 105 integrity and/orquality that are dependent on navigation state (e.g., position,altitude, velocity, time) and also on other factors, such as navigationplatform 12 configuration (e.g., components included in the system),threat data (e.g., physical threats and obstacles, jamming sources),mission plan (e.g., typical factors encountered during a mission,changes to the plan), environment of deployment (e.g., weather,surrounding terrain, surrounding other navigation facilities,surrounding mobile facilities), types of sensor/internal navigationfacility (e.g., common to other multi-sensor navigation platforms,expected performance under conditions), and/or profiles of externalnavigation sources (e.g., RF navigation signals and sources, visualfield data, data channels of navigation data).

The information module 120 uses the models and situation data 125received from the situation module 130 to determine the estimates ofquality and integrity. Because the situation data 125 may changedynamically (as explained below), the information module 120 may updatethe resulting models accordingly. In this manner, the situation data 125is used in the integrity monitor module's 110 initial assessment of thereliability of various data sources 105 and also used in subsequentassessments of the data sources 105 over time.

In some embodiments, the information module 120 may also receive sourceinformation from one or more of the data sources 105 and use this sourceinformation in its models to determine the estimates of integrity andquality. In one embodiment, the information module 120 may determine anestimate of integrity of the source information from one data source 105by comparing it against source information from one or more other datasources 105.

For example, the information module 120 may receive source informationfrom one or more data sources 105 regarding the tides in thegeographical area(s) that the navigation platform(s) have been travelingover, e.g., for the past three hours. The model may be dynamicallyupdated with source information and situation data 125 to reflect anychanges in the tide environment over time. For example, if sourceinformation from a first data source 105 indicates a low tide for thepast three hours and abruptly indicates that the tide is now high, themodel may be updated with the source information from the first datasource 105 and, based on source information from other data sources 105and/or situation data 125 received from the situation module 130, theinformation module 120 may provide an updated estimate of the integrityof the first data source. Similarly, the information module 120 mayreceive source information from one or more data sources 105 related tostars, and the model may be updated to reflect any changes over time.For example, if source information from one data source 105 indicatesthat a star is located at a position that deviates widely from pastsource information from this data source 105 or other data sources 105regarding the same star, the information module 120 may be updated withthe source information from the data source(s) 105 and the informationmodule 120 may use this source information in its model(s) to provide anupdated estimate of the integrity of the data source(s) 105.

In another example, the information module 120 may use situation data125 received from the situation module 130 regarding a newly launchedenemy mission known to be within one or more of the navigationplatforms' vicinity. The information module 120 may use this situationdata 125 to estimate the quality and/or integrity of the sourceinformation from the data sources 105 in the vicinity of one or more ofthe navigation platforms 12 that may be disrupted or spoofed.

In another example, the information module 120 may receive situationdata 125 from the situation module 130 regarding a time of day and usethis situation data 125 along with source information from datasource(s) 105 to provide estimates of the quality and/or integrity usingits statistical models. For instance, celestial objects that orbit theearth are known to provide unreliable source information at certaintimes of the day (e.g., around midnight). Consequently, the informationmodule 120 may use the time of day situation data 125 to estimate thequality and/or integrity of the source information from these celestialobjects over time so that this source information is not used in thenavigation filter system 100 to determine the navigation informationwhen the source information is unreliable, e.g., around midnight.

The information module 120 includes one or more models that describe adynamic and probabilistic state of the source information in order todetermine the estimates of quality and/or integrity of the sourceinformation for each data source 105. When the situation in which thesource information is obtained is fully known, then the informationmodule 120 may use a dynamic and probabilistic state of the sourceinformation. When the situation in which the source information isobtained is uncertain, then the information module 120 may use aprobabilistic state representing the uncertainty associated with thesource information.

For example, the situation data 125 may include low visibility due tofog within the immediate environment of the data source(s) 105. Althoughthe data sources 105, e.g., image sensors, might be functioning properly(i.e., they have good perceived quality), the low visibility mightrender the source information, e.g., the image data, unreliable.Consequently, the information module 120 may use model(s) based on aprobabilistic state in order to determine an estimate of integrity ofthe data sources 105. When the fog lifts and visibility becomes clear,the information module 120 may use model(s) based on a dynamic andprobabilistic state to determine the estimate of integrity of the sourceinformation.

In another example, the situation data 125 may include data indicatingthat enemy vehicles in the vicinity of one or more data sources 105 areequipped with radar jamming devices. The proximity and capabilities ofthe enemy vehicles indicate an uncertain situation with respect to anydata sources 105 that rely on radar in that area. In this situation, theinformation module 120 may use model(s) based on a probabilistic statein order to determine an estimate of integrity of the data sources 105.

The Integrity Monitor Module

The integrity monitor module 110 receives the source informationgenerated by each of the data sources 105 and receives the estimates ofquality and/or integrity from the information module 120 to determinewhether to validate and supply the source information to the navigationstate estimator 115 and, if so, what quality that source informationshould have. As mentioned above, the integrity monitor module 110 maydetermine integrity and/or quality based on information from the datasources 105, information from the information module 120, or both. Theintegrity monitor module 110 sends the validated source information tothe navigation state estimator 115, and in some embodiments, theintegrity monitor module 110 may refrain from sending source informationthat has not been validated.

In some embodiments, the integrity monitor module 110 uses navigationinformation previously generated by the navigation state estimator 115to determine the integrity and/or quality of the source information. Theintegrity monitor module 110 may use multiple techniques to determinethe integrity of source information. For example, the integrity monitormodule 110 may compare z_(i) to a value of the source informationdetermined by the navigation state estimator 115, for instance, in thecase of an extended Kalman filter, h({circumflex over (X)}_(k|k-1)), andcompare the resultant residual (e.g., the difference between z_(i) andthe value determined by the navigation state estimator 115) to thatwhich would be acceptable given the expected quality of that sourceinformation. For example, the resultant residual may be compared to athreshold value and deemed acceptable if it is below the thresholdvalue. In various embodiments, the threshold value may be predetermined,provided dynamically by a sensor, or provided by the information model120.

As mentioned above, the data source 105 that provides the sourceinformation may also provide the quality of that source information, orthe information model 120 may provide expected quality of the sourceinformation, or both the data source 105 and information model 120 mayprovide expected quality. The integrity monitor module 110 may determinethe integrity and/or quality of the source information from the datasource 105 based on a comparison between the source information and itsexpected value and may ignore the source information when the differenceis greater than a quality threshold value or an integrity thresholdvalue and may validate the source information when the quality and/orintegrity of the source information falls within a predeterminedacceptable range. For example, when the information model 120 and thedata source 105 both provide expected quality of the source informationand the values substantially differ (e.g., by a percentage, by anumerical factor, based on a threshold), the integrity monitor module110 may use that difference as a reason to ignore the source informationand not validate it, or the integrity monitor module 110 may overridethe source information quality provided by the data source 105 andreplace it with the information model 120 source information quality andthen validate and pass the source information to the navigation stateestimator 115 with the quality estimate the integrity monitor module 110provides.

When the integrity monitor module 110 validates source information, theintegrity monitor module 110 passes the source information to thenavigation state estimator 115 and also passes the quality of thevalidated source information. As described above, the integrity monitormodule 110 receives the source information from one or more data sources105 and determines the quality and/or integrity of the data sources 105using the estimate of quality and/or integrity from the informationmodule 120 along with the quality and/or integrity of source informationfrom the data sources 105. The source information from the data sources105 may be processed, using standard data processing techniques as knownby one skilled in the art, before the source information is used by theintegrity monitor module 110 and/or the information module 120 andpassed to the navigation state estimator 115. Therefore, the sourceinformation used in the navigation filter system 100 disclosed hereinmay include processed or unprocessed source information.

The Navigation State Estimator

The navigation state estimator 115 uses the validated source informationfrom the integrity monitor module 110 to determine the navigationinformation for one or more navigation platforms 12 in real time. Thenavigation state estimator 115 provides an estimate of the navigationinformation at any given time, regardless of how often the navigationstate estimator 115 receives the validated source information from theintegrity monitor module 110. The navigation state estimator 115 mayfunction using discrete-time Markov processes with a probability densityfunction ƒ(x|{acute over (x)}) that denotes the probability of movingfrom state {acute over (x)} to state x. For example, given some state{X_(n)}_(n≥1), the source information have marginal densities that aregiven by z_(n)|(X_(n)=x_(n))˜g(z_(n)|X_(N)). The implementation of thenavigation state estimator 115 may be accomplished by estimationalgorithms such as an extended Kalman filter, a particle filter, anonlinear moment filter, a Hidden Markov Model, and/or a Bayesianfilter.

Whenever source information, z_(i)′, is available from the integritymonitor module 110, the navigation state estimator 115 updates thenavigation information or state estimate {circumflex over (X)}_(n) basedon whatever additional or new information may be available in the sourceinformation to form the best possible state estimate at that point intime. The navigation state estimator 115 then propagates the navigationinformation or state estimate forward in time as needed by thenavigation filter system 100 and in time increments called navigationepochs that may or may not be regular time intervals. The navigationepoch does not need to be constant and does not need to be synchronizedwith inputs of the validated source information from the integritymonitor module 110 to the navigation state estimator 115. For example,the navigation state estimator 115 may determine the navigationinformation every second, every few seconds, every minute, or every fewminutes, even though the integrity monitor module 110 may be providingvalidated source information to the navigation state estimator 115 intime intervals longer or shorter than the navigation epochs.

As mentioned above, the navigation state estimator 115 may also transmitthe navigation information back to the integrity monitor module 110,where it may be used to validate subsequent source information receivedfrom the data sources 105 and/or information module 120. For example,the navigation state estimator 115 receives accelerations and angularrates from data sources 105, such as accelerometers and gyroscopes. Thissource information may be measured over a period of time, and the resultused to determine the navigation information for one or more navigationplatforms 12. However, misalignment and bias errors are inherent in theaccelerations and angular rates, and both compound over time. When thenavigation state estimator 115 receives a validated and updatedgeolocation position from a GPS system, the source information from theGPS system may be used to bound or otherwise correct for these errors.

As mentioned above, FIG. 7 schematically shows a distributed navigationsystem architecture 10 with a navigation filter system 100 in anenvironment in which the architecture may operate. In this example, thenavigation platform 12 having an anchor navigator 16 and the navigationfilter system 100 is an aircraft (object 101 a). The navigation filtersystem 100 includes numerous data sources 105, such as a GPS satellite,COSS system, stars, planets, and cell phone tower. The data sources 105send source information to the navigation filter system 100.

In one embodiment, the navigation filter system 100 may be configured tocommunicate with other navigation platforms 12 (e.g., aircraft 180,unmanned vehicles 181, personal devices 182 of people, vehicles 183).Any of these objects 180-183 may evaluate the environment of the datasources 105 to obtain situation data 125. Then, the objects may transmitthe situation data 125 to the situation module 130 of the navigationfilter system 100, which, in this embodiment, is located on thenavigation platform 12 shown as the aircraft 101 a. The navigationfilter system 100 may use its situation module 130, information module120, and integrity module 110 to determine which data sources 105 torely on and use in its navigation state estimator 115, as describedabove.

FIG. 8 schematically shows a distributed navigation system architecture10 and environment in which the navigation filter system 100 mayoperate. In this example, the navigation filter system 100 is locatedentirely on a stationary navigation platform 12, such as a base for agovernment agency. Thus, the stationary navigation platform 12 housesthe integrity monitor module 110, the information module 120, thesituation module 130, and the navigation state estimator 115. Thenavigation platform 12 (e.g., aircraft 101 a) receives sourceinformation from data sources 105 such as satellites 105, stars 105,planets 105, and cellphone towers 105 and transmits the sourceinformation to the navigation filter system 100. Furthermore, navigationplatforms 12, such as aircrafts 180, 181 may evaluate the existingenvironment of the data sources 105 to obtain situation data 125, whichis provided to the situation module 130 located on the stationarynavigation platform 12. The navigation filter system 100 uses thereceived situation data 125 and source information from the data sources105 to determine which data sources 105 to rely on and use in itsnavigation state estimator 115, as described above.

FIG. 9 schematically shows a distributed navigation system architecture10 and environment in which the navigation filter system 100 mayoperate. In this example, modules of the navigation filter system 100are distributed across multiple navigation platforms 12, such asdifferent stationary navigation platforms 12, e.g., bases for agovernment agency. One navigation platform 12 may house the integritymonitor module 110, the information module 120, and the situation module130, while the other navigation platform 12 may house the navigationstate estimator 115. One of the navigation platforms 12, e.g., theaircraft 101 a, may receive source information from data sources 105such as satellites 105, stars 105, planets 105, and cellphone towers 105and transmit this information to the integrity monitor module 110 on onenavigation platform 12. The navigation platforms 12 (e.g., objects 180,181) may evaluate the environment of the data sources 105 and providetheir situation data 125 to the situation module 130, which may also belocated on one navigation platform 12. The integrity monitor module 110provides validated source information and corresponding quality of thesource information to the navigation state estimator 115 on the othernavigation platform 12, which uses this information to determine thenavigation information of one or more of the navigation platforms 12(e.g., the navigation platform 12 with the anchor navigator node 16,e.g., aircraft 101 a, as well as the navigation information for theother navigation platforms 12 within the communication network).

Other Features

In various embodiments, one or more components of the distributednavigation system architecture 10 and/or the navigation filter system100 may include one or more processors, memory, an operating system, andone or more programs or applications executing on them to perform thefunctions described herein (also referred to herein as a “computingplatform”). The computing platform may be a stand-alone navigationdevice (e.g., a hand-held navigation device, a body-mounted navigationdevice, a smart phone, a tablet, or the like), a navigation deviceembedded in a user vehicle (e.g., an automobile, a ship, an airplane, atrain, a special-purpose vehicle, or the like), or a navigation deviceembedded in a partially or fully autonomous vehicle (e.g., drone,driverless automobile, robotic device, underwater robotic device,missile, satellite), by way of example. The embodiments of the inventiondescribed above are intended to be merely exemplary; numerous variationsand modifications will be apparent to those skilled in the art. All suchvariations and modifications are intended to be within the scope of thepresent invention as defined by the following claims.

1. A distributed navigation system comprising: a plurality of navigationplatforms, each navigation platform having a universal navigationprocessor configured to communicate with other universal navigationprocessors over distribution channels in a communication network; one ormore relative navigation systems, in communication with the universalnavigation processors, configured to provide source information to thenavigation platforms; one or more navigation filters provided on one ormore of the universal navigation processors, each navigation filterconfigured to process the source information, wherein at least one ofthe one or more navigation filters is configured to apply at least onestatistical model to determine and provide an estimate of the qualityand an estimate of the integrity of the source information; an anchornavigation node disposed on one or more of the plurality of navigationplatforms configured to form one or more anchor navigation platforms,the anchor navigation node including an inertial navigation system, aclock, and one or more absolute navigation systems and configured todetermine navigation information based on the inertial navigationsystem, the clock, the one or more absolute navigation systems and thesource information, the one or more anchor navigation platformsconfigured to provide the navigation information over the distributionchannels to the other navigation platforms in the communication network;a navigation processor system in communication with each of theuniversal navigation processors in the communications network configuredto provide software updates or program code to the universal navigationprocessors; and a graphical user interface configured to display thenavigation information to a user and permit the user to review andcontrol the navigation information.
 2. The distributed navigation systemof claim 1, wherein the graphical user interface is disposed on at leastone of the one or more anchor navigation platforms.
 3. The distributednavigation system of claim 4, wherein at least one of the one or morenavigation filters includes an information module configured todetermine the estimate of the quality and the estimate of the integrityof the source information, at a given time, based on the sourceinformation received from one or more data sources and based on thesituation data received from the situation module.
 4. The distributednavigation system of claim 1, wherein at least one of the one or morenavigation filters includes a situation module, the situation moduleconfigured to receive, from the graphical user interface, an instructionfrom the user and to provide the instruction to the information moduleas situation data.
 5. The distributed navigation system of claim 4,wherein at least one of the one or more navigation filters includes anavigation state estimator configured to determine the navigationinformation of the one or more navigation platforms based on the sourceinformation, wherein the instruction modifies a mission plan to maximizeperformance of one or more of the plurality of navigation platforms. 6.The distributed navigation system of claim 5, wherein the instructionmodifies a mission plan to maintain an estimated arrival time at adestination of one or more of the plurality of navigation platforms. 7.The distributed navigation system of claim 5, wherein the situation datais based on past or current performance of the one or more data sourcesor one or more of the plurality of navigation platforms.
 8. Thedistributed navigation system of claim 5 wherein the situation data isbased on past or current performance of the one or more data sources orone or more of the plurality of navigation platforms in a geographicalregion that overlaps with a mission plan.
 9. The distributed navigationsystem of claim 4, wherein the situation module is configured to receivethe situation data from databases with stored situation data previouslyknown, from communication links with updated situation data that changesover time, from the one or more data sources, from detection systemsthat provide the situation data based on detected conditions, from auser that inputs modifications to the situation data, or any combinationthereof.
 10. The distributed navigation system of claim 4, wherein thesituation data includes environment conditions, position information,velocity, attitude, temporal information, platform configuration,mission phase, data source location, system health, mission plan, threatdata, condition of a threat, threat operating capabilities, threatlocation, temperature, cloud cover, visibility, barometric pressure,terrain, time of year, tides, radiation environment, population, cityinformation, street information, building information, knowntransmitters, known vehicles, visible stars, location of satellites inthe sky, or any combination thereof.
 11. (canceled)
 12. (canceled) 13.(canceled)
 14. The distributed navigation system of claim 1, wherein thegraphical user interface is configured to display information related topast or current performance of one or more of the plurality ofnavigation platforms conducting a mission.
 15. The distributednavigation system of claim 1, wherein the graphical user interface isconfigured to display contributions from the one or more data sources tothe navigation information for one or more of the plurality ofnavigation platforms conducting the mission.
 16. The distributednavigation system of claim 1, wherein the navigation informationincludes position, velocity, altitude, errors in position, errors invelocity, errors in attitude, time, clock errors, propagation delays,GPS satellite errors, sensor errors, sensor characterization parametersor any combination thereof.
 17. The distributed navigation system ofclaim 1, wherein the one or more absolute navigation systems include aglobal positioning system (GPS), a celestial object sighting system(COSS), a magnetic compass, an RF sensor system, or any combinationthereof.
 18. The distributed navigation system of claim 1, wherein theone or more relative navigation systems include a vision system havingan image sensor.
 19. The distributed navigation system of claim 1,wherein the plurality of navigation platforms include moving andnon-moving platforms.
 20. The distributed navigation system of claim 1,wherein the navigation filter includes an extended Kalman filter, aparticle filter, a nonlinear moment filter, a Hidden Markov Model, aBayesian filter or any combination thereof.
 21. The distributednavigation system of claim 3, wherein at least one of the one or morenavigation filters includes an integrity monitor module configured toreceive the estimate of the quality and the estimate of the integrity ofthe source information from the information module and to receive thesource information from the one or more data sources, and configured todetermine the integrity and the quality of the source information basedon the estimate of the quality and the estimate of the integrity of thesource information from the information module, and configured tovalidate the source information based on at least one of the integrityof the source information, and the quality of the source information.22. The distributed navigation system of claim 21, wherein the sourceinformation is validated and corresponds to the estimated of the qualityof the source information received from the integrity monitor module.23. A distributed navigation system comprising: a plurality ofnavigation platforms, each navigation platform having a universalnavigation processor configured to communicate with other universalnavigation processors over distribution channels in a communicationnetwork; one or more relative navigation systems, in communication withthe universal navigation processors, configured to provide sourceinformation to the navigation platforms; one or more navigation filtersprovided on one or more of the universal navigation processors, eachnavigation filter configured to process the source information, whereinat least one of the one or more navigation filters is configured toapply at least one statistical model to determine and provide anestimate of the quality and an estimate of the integrity of the sourceinformation; an anchor navigation node disposed on one or more of theplurality of navigation platforms configured to form one or more anchornavigation platforms, the anchor navigation node including an inertialnavigation system, a clock, and one or more absolute navigation systemsand configured to determine navigation information based on the inertialnavigation system, the clock, the one or more absolute navigationsystems and the source information, the one or more anchor navigationplatforms configured to provide the navigation information over thedistribution channels to the other navigation platforms in thecommunication network; a navigation processor system in communicationwith each of the universal navigation processors in the communicationsnetwork configured to provide software updates or program code to theuniversal navigation processors; and a graphical user interfaceconfigured to display the navigation information to a user and permitthe user to review and control the navigation information, wherein thegraphical user interface is configured to display contributions from theone or more data sources to the navigation information for one or moreof the plurality of navigation platforms conducting the mission.